In recent years, welding, painting and other industrial robots have come into wide use, and various operations such as welding, painting and press-work have been performed by the automatic mechanical power of robots. To take welding, which is typical of such operations, as an example, when an exclusive welding robot suitable for processing certain particular work is introduced to perform few-kind and large-quantity production, a welding jig apparatus must be used to carry in and out work with respect to the robot fixedly installed on the workshop floor and in this case the employment of such a jig apparatus of special construction and function adapted for exclusive use applicable to few kinds of work will suffice for the purpose, whereby operating efficiency can be increased; even if said jig apparatus is custom-made and hence rather expensive, it will pay because of mass production.
However, small and medium-sized enterprises receiving orders from large enterprises which manufacture large-sized products on a mass production basis have often to produce many kinds of assembly parts in small or medium quantities to comply with frequent model changes of large-sized products and to weld parts of complicated welding line in such a manner as not to spil their external appearance. For such rquirements, it would be obviously disadvantageous from the standpoint of operating efficiency and payability to introduce the aforesaid exclusive welding robot and said jig apparatus as its peripheral equipment. Therein lies the practical reason for the need to introduce a versatile welding robot, but the working efficiency of such versatile welding robot is not yet very high. Even if such robot itself has excellent versatility, unless the jig apparatus used to carry in and out work with respect to the robot is lacking in the versatility to comply with a large variety of changes in the kind of work, the result would be the same, since it is still impossible to increase working efficiency. Further, such jig apparatus must be inexpensive so that even small and medium-sized enterprises can afford to introduce it, and must be easy to use so that anyone can master it without being required to have expert technical knowledge. With these various conditions taken into consideration, the present situation is that it is difficult for small and medium-sized enterprises to find an optimum jig apparatus. It seems that similar problems may be said of the fields of painting, slodering, fusion cutting and press work, apart from the aforesaid welding operation.